THE SYNTHESIS OF ENDO-3-DIPHENYLPHOSPHINO-(1R)-(+)-CAMPHOR (L) AND SOME OF ITS COMPLEXES WITH PALLADIUM(II), PLATINUM(II) AND RHODIUM(I) - CRYSTAL-STRUCTURES OF L AND CIS-[PDCL2L2]

Treatment of (1R)-(+)-camphor with LiBun, followed by Ph2PCl gives, as the main product, exo-3-diphenylphosphino-(1R)-(+)-camphor (3a) together with some of the corresponding enolate anion 1. However, on storage the exo-phosphine 3a isomerises to the corresponding endo-phosphine 3b which becomes the main product and was isolated in 70% yield. The crystal structure of 3b was determined and detailed C-13 and proton NMR data are given. In chloroform solution, in the presence of acetic acid as catalyst, the endo-phosphine 3b is partially converted back into the exo-isomer 3a over 2 days. The endo-phosphine 3b (L) with H2O2 gives the corresponding phosphine oxide 3c and with monoclinic sulfur the corresponding phosphine sulfide 3d. With [PdCl2(NCPh)2] the endo-phosphine 3b gives [PdCl2L2] which exists as a cis-trans mixture 4a and 4b in solution. We have determined the X-ray crystal structure of the cis-form 4b. Treatment of [PtC]2(COD)] with L, gives cis-[PtCl2L2] (4c) but with [PtCl2(NCMe)2] the corresponding trans complex trans-[PtCl2L2] (4d) is formed. In compounds 4a-4d the PPh2 groups are endo. The complexes of type [MCl2L2] (M = Pd or Pt) are also formed by treating the bis-camphorphosphine enolates [M(PPh2C10H14O)2] with HCl. The complexes of type cis-[Pt(C-CR)2(PPh2C10H15O)2] (R = Ph or C(Me) = CH2) with HCl give exclusively cis-[PtCl2L2]. Treatment of [Rh2Cl2(CO)4] with the endo-phosphine 3b (L) gives trans-[RhCl(CO)L2]. H-1, P-31 and some C-13 data are given. Crystals of endo-3-diphenylphosphino-(1R)-(+)-camphor (3b) are orthorhombic, space group P2,212, with a = 778.6(l), b = 1138.8(l), c = 2128.9(3) pm and Z = 4, R = 0.0329 for 1674 observed reflections. The structure shows that the PPh2 is endo. Crystals of 4b are orthorhombic, space group P2(1)2(1)2(1) with a = 1380.3(2), b = 1785.1(3), c = 1922.8(4) pm and Z = 4, R = 0.0425 for 4438 observed reflections. The structure shows that the PPh2 groups are endo and that the phosphines are cis.